How much water does hotel air conditioning produce?

In a humid climate, cooling yields roughly 0.3-0.85 litres of condensate per kWh of cooling delivered, and a hotel room typically draws 10-26 kWh of cooling per occupied night. Only part of that is collectable: capture ranges from around 55-90% on central chilled-water plant down to 15-50% on scattered split units.

What can AC condensate be used for?

Cooling-tower make-up is the strongest match, because condensate is low in dissolved solids and the demand sits next to the source. Irrigation and toilet flushing are also common. It is not potable and must never be cross-connected with the potable network.

It is near-distilled when it leaves the coil, but it can pick up metals, biofilm and Legionella risk from drain pans and pipework. Filtration is the minimum, and a qualified engineer must specify treatment and monitoring for the intended end use.

Why is condensate recovery worth looking at first?

It peaks exactly when cooling load and irrigation demand peak, so supply and demand are naturally in phase - unusual among recoverable streams - and the capital involved is generally small compared with greywater treatment.

Recoverable stream

Air-conditioning condensate recovery.

Every cooling coil in the building is a small water source. In humid climates a hotel condenses roughly 0.3-0.85 litres of near-distilled water per kWh of cooling delivered, and almost all of it goes to drain. Whether it is worth capturing depends far less on the climate than on how your cooling plant is arranged.

Start a free Water Snapshot How these numbers are derived

Published coefficients for condensate

These are the exact bands the Aquiterum engine applies. Nothing here is a vendor figure.

Figure	Value	Evidence	Source
Condensate yield, humid climateLitres condensed per kWh of cooling delivered. Very humid coasts run higher, arid inland sites far lower.	0.3-0.85 L/kWh	benchmark	Sustainability (MDPI) — Magrini, Cattani, Cartesegna, Magnani, 2017; Journal of Physics: Conference Series — Khan et al., 2026; Water Resources Management (Springer) — open access, 2025
Condensate yield, arid climateDry air holds little moisture, so the same cooling load yields a fraction of the water.	0.05-0.2 L/kWh	benchmark	Sustainability (MDPI) — Magrini, Cattani, Cartesegna, Magnani, 2017; Journal of Physics: Conference Series — Khan et al., 2026; Water Resources Management (Springer) — open access, 2025
Cooling delivered per occupied room nightHumid-climate band. Multiply by the yield above to get theoretical condensate.	10-26 kWh	benchmark	Sustainability (MDPI) — Magrini, Cattani, Cartesegna, Magnani, 2017; Journal of Physics: Conference Series — Khan et al., 2026; Water Resources Management (Springer) — open access, 2025
Capture rate, central chilled-water plantFew, large, accessible drain points make collection straightforward.	55-90%	modelled	Sustainability (MDPI) — Magrini, Cattani, Cartesegna, Magnani, 2017; Journal of Physics: Conference Series — Khan et al., 2026; Water Resources Management (Springer) — open access, 2025
Capture rate, individual split unitsDozens of scattered drains, most discharging outside. This is what usually kills the business case.	15-50%	modelled	Sustainability (MDPI) — Magrini, Cattani, Cartesegna, Magnani, 2017; Journal of Physics: Conference Series — Khan et al., 2026; Water Resources Management (Springer) — open access, 2025

Bands, not point estimates. Aquiterum carries low, likely and high values end to end rather than collapsing them into one flattering number.

Blind spot

Why it gets missed

It is produced continuously, distributed across the whole building, and every drain run looks like a nuisance rather than a resource.

Peaks exactly when cooling load and irrigation demand peak — one of the few streams naturally in phase with summer demand.

Next use

Where condensate can go

Cooling-tower make-up - the best match: low dissolved solids, and the demand is metres from the source.
Landscape irrigation - in phase with peak summer demand, though storage is usually needed to buffer overnight.
Toilet flushing - viable where a non-potable riser already exists or can be routed.

Caution. Condensate is low in dissolved solids but can pick up metals, biofilm and Legionella risk from drain pans and pipework. It is not potable and must not be cross-connected with the potable network.

Common questions

How much water does hotel air conditioning produce?: In a humid climate, cooling yields roughly 0.3-0.85 litres of condensate per kWh of cooling delivered, and a hotel room typically draws 10-26 kWh of cooling per occupied night. Only part of that is collectable: capture ranges from around 55-90% on central chilled-water plant down to 15-50% on scattered split units.
What can AC condensate be used for?: Cooling-tower make-up is the strongest match, because condensate is low in dissolved solids and the demand sits next to the source. Irrigation and toilet flushing are also common. It is not potable and must never be cross-connected with the potable network.
Is condensate clean?: It is near-distilled when it leaves the coil, but it can pick up metals, biofilm and Legionella risk from drain pans and pipework. Filtration is the minimum, and a qualified engineer must specify treatment and monitoring for the intended end use.
Why is condensate recovery worth looking at first?: It peaks exactly when cooling load and irrigation demand peak, so supply and demand are naturally in phase - unusual among recoverable streams - and the capital involved is generally small compared with greywater treatment.

Related guides

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